It has previously been proposed to make rod-like material or tubular material by assembling canes adjacent each other, and retaining the canes in a predetermined cross-sectional shape by wrapping the canes with an external wrapping or roving material. German Utility Model Publication No. 71 14 991, published July 15, 1971, describes a hollow structure in which a plurality of reinforcing rods in the form of glass fiber canes are first placed within depressions of a metal core, forming a mandrel, the canes then are wrapped with a glass-fiber roving, which includes a curable epoxy. After preliminary curing of the epoxy, the metal core or mandrel is removed--it is not stated how--and what is left will be the glass-fiber wrapping, longitudinally reinforced by the reinforcing glass fiber canes then located internally of the cured glass fiber wrap, now tubular structure. It has also been proposed--see German Patent Disclosure Document DE-OS No. 24 26 015--to form a hollow body by locating longitudinal stabilization strips surrounding an extruded inner tube, the stabilization strips being located uniformly distributed about the circumference and having glass-fiber-reinforced plastic positioned between the stabilization strips. In order to form a closed outer circumference, glass-fiber tapes or bands, with a hardenable compound, are then wrapped about the rods placed circumferentially around the inner extruded tube. The entire assembly is then permitted to cure or harden.
Rod-like material is frequently required in many fields of industry, and it is often necessary to assemble rod-like or columnar material longitudinally to obtain longer lengths than those first delivered or available, or to cut predetermined lengths of material from long rods or columns. It is also frequently necessary to provide columnar material with laterally extending branch elements. In accordance with the prior art, the rod-like material must, then, be cut to length or, if to be extended, in case of metal to be welded together. Cutting to length, longitudinally extending by welding, and/or branching, requires frequently slanting and often complicated cuts which substantially increases the cost of manufacture of a given rod-like or columnar or bar-like structure, particularly if lateral branches are also needed. Matching the specific structure and its shape to particular requirements is often expensive and time-consuming, and the requisite technology of joining connecting elements requires skill and patience, and hence expense to the user.